LOCATION TOWAOC COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haplustalfs
TYPICAL PEDON: Towaoc very gravelly sandy loam, on a northeast facing, 60 percent slope in Gambel oak at an elevation of 8400 feet. (Colors are for dry soil unless otherwise noted.) When described on Sept. 19, 2002 the soil was dry throughout. The surface is covered by 1 inch of leaf litter.
A1--0 to 2 inches; brown (7.5YR 4/2) very gravelly sandy loam, dark brown (7.5YR 3/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky, slightly plastic; many very fine, common fine, few medium, and few coarse roots throughout; 30 percent gravel, 5 percent cobbles and 1 percent stones; noneffervescent; slightly acid (pH 6.2); clear smooth boundary. (1 to 6 inches thick)
A2--2 to 5 inches; brown (7.5YR 4/2) very gravelly sandy loam, dark brown (7.5YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; many very fine, common fine roots, few medium, and few coarse roots throughout; 30 percent gravel, 5 percent cobbles and 1 percent stones; noneffervescent; neutral (pH 6.6); clear smooth boundary. (0 to 6 inches thick)
BA--5 to 12 inches; brown (7.5YR 4/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine, common fine roots, few medium, and few coarse roots throughout; few very fine dendritic tubular pores; 35 percent gravel, 15 percent cobbles and 1 percent stones; noneffervescent; neutral (pH 7.0); clear smooth boundary. (0 to 8 inches thick)
Bt1--12 to 28 inches; brown (7.5YR 4/4) very gravelly sandy loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine, common fine, few medium, and few coarse roots throughout; few very fine dendritic tubular pores; 15 percent patchy distinct clay films on all faces of peds; 35 percent gravel, 15 percent cobbles and 1 percent stones; noneffervescent; neutral (pH 7.0); gradual smooth boundary. (10 to 28 inches thick)
Bt2--28 to 41 inches; strong brown (7.5YR 4/6) very gravelly loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; moderately hard, friable, slightly sticky, slightly plastic; common very fine, common fine, few medium, and few coarse roots throughout; 25 percent patchy distinct clay films on all faces of peds; 35 percent gravel, 15 percent cobbles and 1 percent stones; noneffervescent; neutral (pH 7.0); gradual smooth boundary. (10 to 30 inches thick)
Bt3--41 to 56 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; moderately hard, friable, slightly sticky, slightly plastic; common very fine, common fine, few medium, and few coarse roots throughout; 50 percent patchy distinct clay films on all faces of peds; 35 percent gravel, 15 percent cobbles and 1 percent stones; noneffervescent; neutral (pH 7.0); gradual smooth boundary. (0 to 20 inches thick)
Bt4--56 to 80 inches; brown (7.5YR 5/4) very gravelly loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure, and moderate medium subangular blocky structure; moderately hard, friable, slightly sticky, slightly plastic; common very fine, common fine, few medium, and few coarse roots throughout; 60 percent patchy distinct clay films on all faces of peds; 35 percent gravel, 15 percent cobbles and 1 percent stones; noneffervescent; neutral (pH 7.2); gradual smooth boundary.
TYPE LOCATION: Montezuma County, Colorado; about 7 miles west of Towaoc; located about 1,200 feet west and 300 feet south of the northeast corner of sec. 3, T. 34 N., R. 18W.; Mariano Wash East, Colorado USGS quad; lat. 37 degrees 14 minutes 22.03 seconds N. and long. 108 degrees 48 minutes 51.10 seconds W., NAD 83.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is typic ustic.
Mean annual soil temperature: 44 to 47 degrees F
Depth to argillic horizon: 8 to 16 inches
Rock fragments are extremely hard in the upper part of the profile, while some rock fragments are more highly weathered in the lower part of the profile.
Particle-size control section (weighted average):
Clay content: 10 to 18 percent
Rock fragment content: 35 to 90 percent, dominantly gravel and cobble
A horizon:
Hue: 7.5YR or 10YR
Value: 3 or 4, 2 to 4 moist
Chroma: 2 or 3
Texture: sandy loam or loam
Rock fragment content: 35 to 90 percent, dominantly gravel and cobble
Clay content: 5 to 15 percent
Reaction: Slightly acid to neutral
Bt horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5, 2 to 4 moist
Chroma: 4 to 6
Texture: sandy loam or loam
Rock fragment content: 35 to 90 percent, dominantly gravel and cobble
Clay content: 10 to 27 percent
Reaction: Slightly acid to neutral
COMPETING SERIES: These are the Abreu, Colomex, Laventana, Littlewater, Macmeal, Mocmont, Namon, Sheek, Skyview, Sonsela, Tecolote, Trapps, Vision, Wahatoya, Xankey, Ymark, Yourame, and Yreka series.
Abreu: have a lithic contact at 40 to 60 inches.
Colomex: have less than 18 percent clay in the particle-size control section.
Laventana: have a lithic contact at 40 to 60 inches.
Macmeal: have accumulations of secondary calcium carbonate.
Mocmont: have a glossic horizon.
Namon: have lithic contact between 40 to 60 inches over sandstone.
Sheek: have less than 18 percent clay in the particle-size control section
Skyview: have a lithic contact at 23 to 40 inches.
Sonsela: have less than 18 percent clay in the particle-size control section.
Tecolote: have albic horizons.
Trapps: have albic horizons.
Vision: have less than 18 percent clay in the particle-size control section.
Wahatoya: have a lithic contact at 20 to 40 inches.
Xankey: have less than 18 percent clay in the particle-size control section.
Ymark: have a lithic contact at 43 to 60 inches.
Yourame: have horizons of secondary carbonate accumulation.
Yreka: have less than 18 percent clay in the particle-size control section.
GEOGRAPHIC SETTING:
Parent material: Colluvium and slope alluvium derived from diorite and other intrusive igneous material
Landform: Mountain Slopes
Slopes: 6 to 75 percent
Elevation: 7,500 to 9,000 feet
Mean annual temperature: 42 to 45 degrees F
Mean annual precipitation: 16 to 20 inches
Precipitation pattern: Uniform with slight dip in May and June and slight increase in July and August.
Frost-free period: 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Littlewater (T), Wetoe (T), and Nees (T) series. The Littlewater soils have E horizons and are on mountain slopes under Douglas Fir woodland. The Wetoe soils are very deep on mountain slopes and are on warmer south aspects. The Nees soils are shallow and are on warmer south aspect mountain slopes.
DRAINAGE AND PERMEABILITY: Well drained, slow runoff, moderately rapid permeability.
USE AND VEGETATION: This soil is used for watersheds. Potential native vegetation is mainly Gambel oak, Utah serviceberry, snowberry, slender wheatgrass, and muttongrass.
DISTRIBUTION AND EXTENT: Sleeping Ute Mountains, southwest Colorado; MLRA 36; small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Montezuma County, Colorado; Ute Mountain Area, Colorado and New Mexico, 2005.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 79 inches.
Particle-size control section: The zone from 11 to 40 inches. (Bt1, Bt2 horizons)
Ochric epipedon: The zone from 0 to 5 inches. (A1, A2 horizons)
Argillic horizon: The zone from 12 to 32 inches. (Bt1, and part of the Bt2 horizons)
The assignment of the cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003.